For the protection of worker health, many industries have utilized air sampling apparatuses to determine the presence of harmful gaseous compounds which the worker may breathe. The determination of the quality of air in the work area breathed by the worker is oftentimes determined by having the worker carry with him, through a typical working day, an apparatus which is capable of sampling the air at a constant rate over a specified period.
Personal air sampling apparatuses worn generally include an electric pump and metering device which pumps a known volume of air into a gas collection reservoir over a known period of time. A metering device is used to help maintain a constant pump rate. Driving these pumps are batteries which require battery rechargers to recharge the battery after it has been used during a sampling period. Also, since the electric pump type apparatuses are not able to hold all of the air pumped during the day, these type apparatuses utilize an adsorbing section, to adsorb from the air particular compounds which are being monitored. After the sampling period the adsorbent is removed from the apparatus and measurement is made of the various components adsorbed. In some instances the adsorbent is regenerative but in other cases it must be thrown away. A drawback in utilizing adsorbents is that the adsorbent utilized must be particularly chosen for the particular component that is sought to be identified in the air. Should there be a component in the air which has not been anticipated, or one which is not adsorbed by the particular adsorbent utilized, this particular component--even though harmful to the worker--may go undetected. Also, the component must be desorbed from the adsorbent for analysis, thus leading to analytical errors.
Therefore it is seen that present day apparatuses, while useful, have drawbacks in that they require expensive electrical pumps, batteries and battery rechargers and also they have very poor broad spectrum capabilities.
Thus it is an object of this invention to provide an air collection apparatus which automatically collects an accurate time-weighted air sample which is not dependent upon energized collection means, operator attention, and which is capable of broad spectrum collection.